starter sometimes does not engage

My bike (which I have only owned for a month and barely ridden) was sitting for a few weeks while I replaced the tires. This morning I decided to jump start it and take it to work. I hooked it up to my car battery and cranked it and a lot of water shot out of the exhaust pipe... stupid straight pipe is angled up and apparently collected filth water in it.

I ran the starter about 8 times for 3-5 seconds each time, until the engine started stumbling but not quite catching. I thought it was going to catch the next time I did it, but instead: WHIRRRRRRRRRRRR chunk chunk chunk. Waited 5 minutes, tried again.. repeated 4 times. Every time: WHIRRRRRRRRR chunk chunk chunk. I figured my starter was shot

As a last resort, I ran the sucker down a hill and it started right up when I dropped the clutch. Hurray! So, being the dummy that I am, I put on my gear and rode to work. I got about 5 miles before the damned thing stumbled and stalled as I started to leave a red light. At this point I figured I was screwed: stalled in the middle of a 7 lane road at rush hour and my starter is dead. But I tried and the starter actually turned the engine over and started on about the 4th try. It died AGAIN at that light, and the starter was starting to get slow but it finally did catch. I rode the rest of the way to work without letting the RPMs drop below 1,000 when I stopped. It was mostly paranoia, I think it idles fine and I just stalled it by slipping the clutch a little too fast when I started to move.

What causes the whirring noise of the starter motor going but not catching? Is that a 'starter clutch', and am I going to need to replace it? The bike had been sitting for about a month, and the oil in it is ancient and going to be replaced this weekend if that makes any difference. Aside from the starting issues, the engine seems to run and sound smooth and has plenty of power. No problem cruising at 70 mph.

 

First comment, what were you thinking???? I'm sure that comment smarts, we have all pulled our proverbial dummies in our eager youth so don't feel too bad.
While the bike was sitting, why didn't you change out the oil? I'll go out on a limb here and say that I think your problem will go away with an oil change or two. Here is why: the starter clutch has sprags in it with springs and rollers. The pieces parts won't move up and down in their respective bores because of the ancient oil being unable to properly clean and lubricate the assembly. It is a sound bet that the regular preventative maintenance was not performed and you have a sticky varnish/goo inside the clutch assembly.
An oil change at best should fix it. At worst, you will need to pull the alternator and associated shaft to access the clutch assembly and hose out the clutch roller bores with a good carb or brake cleaner. Be ready to change the oil again afterwards.
You may also wish to take this opportunity to pull your starter and give it a good cleaning while checking the brushes and re-lubricating the internal gears.
As to the starting issues, have you cleaned out the carbs? I'll bet if you do, you will find the bikes runs better/more reliably. There are a few VERY good threads on the forum on how to preform this task. (authors Rick-O-Matic and Gamaru come to mind)

 

Thanks for the info, it relaxes my fear a bit. I was praying that it's sticky oil residue and not an actual bad starter clutch, since I read that replacing the clutch requires pulling the engine.

Oil change, followed by another oil change, and maybe a seafoam oil change, and then maybe some more oil changes are in line for this weekend. I was yelled at for working on the bike at my apartment (apparently against HOA), so I needed to get it to my parents house for the overhaul. I work near my parents' house, hence riding to work today.

I noticed today that when the electric starter did work, it didn't catch until I released the button. I believe that means the brushes need to be replaced? Looks like I can add starter rebuild to the list. Carbs and starter are both on the "I'll do it if it seems necessary after I get a little more riding time." Only 3 rides on the bike since getting it, so I don't know all of its quirks yet.

 

"Only 3 rides on the bike since getting it"

STOP RIGHT THERE. Have you checked the rear brake for delamination?
http://xjbikes.com/Forums/viewtopic/t=15874.html Hopefully you looked when replacing the tires?

If NOT, move that to the TOP of your list, and quit riding it until you do.

Seriously.

 

Yes, I checked them when I had the wheels off and they were fine. I bought replacements regardless, but they aren't on yet.

The bike fired up instantly with the starter last night, so that's certainly promising.

 

it sounds weird but check the battery and starter motor brushes. Both/either of these will give you weak starts and as soon as one cylinder fires one time the starter clutch disengages and the weak starter won't reengage.

and yes, like Fitz said, you are currently playing russian roulette with your ass end.